UI Issues for Quixel Mixer 2022.1.1 Beta

I have issues with my Quixel Mixer UI,
every time I add a custom model (which is the type of format I’m working on) and open the “Edit Materials” and/or "Edit Texture Sets " menu, for some reason I’m unable to close it, there’s no X button on the menu window. I tried pressing Esc but it doesn’t exit the window. Am I the only one having this issue?